Mumbo Jumbo lives with his mother in a small valley, but one day he accidentally eats a mysterious mushroom and suddenly grows to an enormous size. He becomes so big that he can no longer fit inside the cozy little house he shares with his mother. Luckily, a mandrill named Frede finds a solution to the problem, but it lies in Siberia, and Mumbo has to get there on foot. Oh, and he also needs to seek out the witch Baba Yaga. Mumbo’s best friends—Tapir, Cheetah, and Mimbo Jimbo—join him on this journey.